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black smoke under load with 671ti

so i have a 93 luhrs 3800 tournament series with twin 671 ti's the problem is i get a lot black smoke and sometimes some unburnt fuel and/or oil out the exhaust. it is happening with both engines and since this has started i have had the fuel tank polished, changed the fuel/water separators, both of the air seps, and the fuel filters. it still wont climb higher than 1200 rpm's without blowing out tons of smoke and really seems to struggle to get up any further then that. also when its not under load i can easily get up to 1800 rpms with no smoke.

Re: black smoke under load with 671ti

OK, this might sound bad but don't know when they were serviced.. i bought this boat in 08 and they told me the engines were completely over-hauled and i had a marine inspector and mechanic come out, they both gave it there stamp of approval. i also believe they are 671 ti's not 671 tia's so they might not have an after-cooler... i also don't know what i should be looking for when you say inter-coolers(sounds horrible i know, but i am still learning all about these engines)

also would i be able to service the inter-coolers or should it be a professional??

Re: black smoke under load with 671ti

Air charge cooler= air enters the intake ducting, gets filtered then to a cooler then to the turbo and on to the engine.

Inter-cooler= air enters the intake ducting, gets filtered, enters the turbo then enters the cooler and on to the engine.

After-cooler= these are coolers placed underneath (or after) the blower and heat is transferred through engine cooling system. The blower can oil the after-cooler, causing it to clog and reduce air flow. This could cause your symptoms if the rotor seals begin to leak.